Bureau for measures and precious metals, Belgrade, Serbia and Montenegro

Abstract. The national standard spectrophotometric system developed in the Laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals (ZMDM) is used for realization of regular spectral transmittance scale in spectral region 360 nm to 1000 nm. Evaluation of the performances of the system shows that the measurements on neutral density filters can be performed with the uncertainties in range from 0.1 % to 2 % (k = 2), depending on transmittance level and wavelength. System verification was performed according to NIST SRM reference standards. The validation of the method is expected with the results of EUROMET key comparison of regular spectral transmittance, in which, the Laboratory for photometry of ZMDM was included through the- bilateral comparison of regular spectral transmittance measurements with INM (EUROMET project No 766). Realization of the system and the method used in that bilateral comparison, together with its metrological characterization and measurement uncertainty evaluation, are presented in this paper